Most present day offices include telephones and computers. Office suites generally have a PBX or key system to handle the telephones and a separate Data Router to interconnect computers via a LAN.
Telephone key systems and PBX systems are available in a wide variety of forms. Most such systems are built using special purpose hardware. However, recently, programmed personal computers have been used to implement telephone switching systems. Such systems use the multitasking capabilities of computers such a the Microsoft Windows NT system to simultaneously switch a number of telephone calls between local loops and from local loops to trunk circuits.
The LANs used in office suites generally interconnect computers through Data Routers. A number of companies including Cisco Systems Inc., and AT&T market Routers for LAN networks.
In general, telephone systems and computer networks are moving toward similar technologies. This movement has been accelerated by the advent of “Internet Telephony”. Internet Telephones transmit digitized and packetized voice over computer LAN networks and over the Internet.
Recently, systems have become available which integrate in one unit both, telephone switching or PBX capabilities, and LAN Data Routing or switching capabilities. Such integrated systems can function as both a small PBX and as a LAN Data Router. Presently available integrated systems use the multitasking capabilities of computer systems (such as the multitasking capabilities of the Microsoft Windows NT system) to handle multiple tasks on a time slice basis. Such systems can both switch telephone lines and they can also route data packets traveling over a LAN network.
Recurring cost for wide area network links dominates the overall service cost when providing either telephone or data communication networks. Because of this significant value is provided by equipment that can achieve higher wide area network utilization rates.